The public sector is under pressure to do things differently, and less costly. Therefore, organizations in the public sector are increasingly expected to be innovative. However, prior theory and research show that the development and implementation of innovation is far from easy for most organizations. However, there has been scant research on this issue focusing on the public sector. Reflecting this gap, this study seeks to explain obstacles to innovation and their severity within public sector organizations. While scholars have suggested that public sector organizations are confronted with many and severe obstacles to innovation, there is a lack of theorizing and systematic research of this issue. Combining theorizing on the innovation process with institutional theory, we suggest that the severity of obstacles to innovation is a function of different types of pressures. To examine this, we use cross-national survey data on public sector organizations from 27 countries and regression analysis. Our findings show that the severity of obstacles to innovation, emerges from the process of innovation itself, but also is a function of coercive external pressures confronting the organization (attempting) to innovate. In sum, our study shed new theoretical and empirical light over obstacles to innovation within public sector organizations.